Age-related changes in amplitude, latency and specialization of ERP responses to faces and watches

Healthy aging is associated with impairments in face recognition. While earlier research suggests that these impairments arise during memory retrieval, more recent findings suggest that earlier mechanisms, at the perceptual stage, may also be at play. However, results are often inconsistent and very few studies have included a non-face control stimulus to facilitate interpretation of results with respect to the implication of specialized face mechanisms vs. general cognitive factors. To address these issues, P100, N170 and P200 event-related potentials (ERPs) were measured during processing of faces and watches. For faces, age-related differences were found for P100, N170 and P200 ERPs. For watches, age-related differences were found for N170 and P200 ERPs. Older adults showed less selective and less lateralized N170 responses to faces, suggesting that ERPs can detect age-related de-differentiation of specialized face networks. We conclude that age-related impairments in face recognition arise in part from difficulties in the earliest perceptual stages of visual information processing. A working model is presented based on coarse-to-fine analysis of visually similar exemplars.

Orientation-invariance of individual differences in three face processing tasks

Numerous studies have reported impairments in perception and recognition, and, particularly, in part-integration of faces following picture-plane inversion. Whether these findings support the notion that inversion changes face processing qualitatively remains a topic of debate. To examine whether associations and dissociations of the human face processing ability depend on stimulus orientation, we measured face recognition with the Cambridge Face Memory Test (CFMT), along with experimental tests of face perception and selective attention to faces and non-face objects in a sample of 314 participants. Results showed strong inversion effects for all face-related tasks, and modest ones for non-face objects. Individual differences analysis revealed that the CFMT shared common variance with face perception and face-selective attention, however, independent of orientation. Regardless of whether predictor and criterion had same or different orientation, face recognition was best predicted by the same test battery. Principal component decomposition revealed a common factor for face recognition and face perception, a second common factor for face recognition and face-selective attention, and two unique factors. The patterns of factor loadings were nearly identical for upright and inverted presentation. These results indicate orientation-invariance of common variance in three domains of face processing. Since inversion impaired performance, but did not affect domain-related associations and dissociations, the findings suggest process-specific but orientation-general mechanisms. Specific limitations by constraints of individual differences analysis and test selection are discussed.

The Two-Systems Account of Theory of Mind: Testing the Links to Social- Perceptual and Cognitive Abilities

According to the two-systems account of theory of mind (ToM), understanding mental states of others involves both fast social-perceptual processes, as well as slower, reflexive cognitive operations (Frith and Frith, 2008; Apperly and Butterfill, 2009). To test the respective roles of specific abilities in either of these processes we administered 15 experimental procedures to a large sample of 343 participants, testing ability in face recognition and holistic perception, language, and reasoning. ToM was measured by a set of tasks requiring ability to track and to infer complex emotional and mental states of others from faces, eyes, spoken language, and prosody. We used structural equation modeling to test the relative strengths of a social-perceptual (face processing related) and reflexive-cognitive (language and reasoning related) path in predicting ToM ability. The two paths accounted for 58% of ToM variance, thus validating a general two-systems framework. Testing specific predictor paths revealed language and face recognition as strong and significant predictors of ToM. For reasoning, there were neither direct nor mediated effects, albeit reasoning was strongly associated with language. Holistic face perception also failed to show a direct link with ToM ability, while there was a mediated effect via face recognition. These results highlight the respective roles of face recognition and language for the social brain, and contribute closer empirical specification of the general two-systems account.

On Response Bias in the Face Congruency Effect for Internal and External Features

Some years ago Cheung et al. (2008) proposed the complete design (CD) for measuring the failure of selective attention in composite objects. Since the CD is a fully balanced design, analysis of response bias may reveal potential effects of the experimental manipulation, the stimulus material, and/or attributes of the observers. Here we used the CD to prove whether external features modulate perception of internal features with the context congruency paradigm (Nachson et al., 1995; Meinhardt-Injac et al., 2010) in a larger sample of N = 303 subjects. We found a large congruency effect (Cohen's d = 1.78), which was attenuated by face inversion (d = 1.32). The congruency relation also strongly modulated response bias. In incongruent trials the proportion of “different” responses was much larger than in congruent trials (d = 0.79), which was again attenuated by face inversion (d = 0.43). Because in incongruent trials the wholes formed by integrating external and internal features are always different, while in congruent trials same and different wholes occur with the same frequency, a congruency related bias effect is expected from holistic integration. Our results suggest two behavioral markers of holistic processing in the context congruency paradigm: a performance advantage in congruent compared to incongruent trials, and a tendency toward more “different” responses in incongruent, compared to congruent trials. Since the results for both markers differed only quantitatively in upright and inverted presentation, our findings indicate no change of the face processing mode by picture plane rotation. A potential transfer to the composite face paradigm is discussed.

Object Localization Does Not Imply Awareness of Object Category at the Break of Continuous Flash Suppression

In continuous flash suppression (CFS), a dynamic noise masker, presented to one eye, suppresses conscious perception of a test stimulus, presented to the other eye, until the suppressed stimulus comes to awareness after few seconds. But what do we see breaking the dominance of the masker in the transition period? We addressed this question with a dual-task in which observers indicated (i) whether the test object was left or right of the fixation mark (localization) and (ii) whether it was a face or a house (categorization). As done recently Stein et al. (2011a), we used two experimental varieties to rule out confounds with decisional strategy. In the terminated mode, stimulus and masker were presented for distinct durations, and the observers were asked to give both judgments at the end of the trial. In the self-paced mode, presentation lasted until the observers responded. In the self-paced mode, b-CFS durations for object categorization were about half a second longer than for object localization. In the terminated mode, correct categorization rates were consistently lower than correct detection rates, measured at five duration intervals ranging up to 2 s. In both experiments we observed an upright face advantage compared to inverted faces and houses, as concurrently reported in b-CFS studies. Our findings reveal that more time is necessary to enable observers judging the nature of the object, compared to judging that there is “something other” than the noise which can be localized, but not recognized. This suggests gradual transitions in the first break of CFS. Further, the results imply that suppression is such that no cues to object identity are conveyed in potential “leaks” of CFS (Gelbard-Sagiv et al., 2016).

Contextual Interactions in Grating Plaid Configurations Are Explained by Natural Image Statistics and Neural Modeling

Processing natural scenes requires the visual system to integrate local features into global object descriptions. To achieve coherent representations, the human brain uses statistical dependencies to guide weighting of local feature conjunctions. Pairwise interactions among feature detectors in early visual areas may form the early substrate of these local feature bindings. To investigate local interaction structures in visual cortex, we combined psychophysical experiments with computational modeling and natural scene analysis. We first measured contrast thresholds for 2 × 2 grating patch arrangements (plaids), which differed in spatial frequency composition (low, high, or mixed), number of grating patch co-alignments (0, 1, or 2), and inter-patch distances (1° and 2° of visual angle). Contrast thresholds for the different configurations were compared to the prediction of probability summation (PS) among detector families tuned to the four retinal positions. For 1° distance the thresholds for all configurations were larger than predicted by PS, indicating inhibitory interactions. For 2° distance, thresholds were significantly lower compared to PS when the plaids were homogeneous in spatial frequency and orientation, but not when spatial frequencies were mixed or there was at least one misalignment. Next, we constructed a neural population model with horizontal laminar structure, which reproduced the detection thresholds after adaptation of connection weights. Consistent with prior work, contextual interactions were medium-range inhibition and long-range, orientation-specific excitation. However, inclusion of orientation-specific, inhibitory interactions between populations with different spatial frequency preferences were crucial for explaining detection thresholds. Finally, for all plaid configurations we computed their likelihood of occurrence in natural images. The likelihoods turned out to be inversely related to the detection thresholds obtained at larger inter-patch distances. However, likelihoods were almost independent of inter-patch distance, implying that natural image statistics could not explain the crowding-like results at short distances. This failure of natural image statistics to resolve the patch distance modulation of plaid visibility remains a challenge to the approach.

Contour integration with corners

Contour integration refers to the ability of the visual system to bind disjoint local elements into coherent global shapes. In cluttered images containing randomly oriented elements a contour becomes salient when its elements are coaligned with a smooth global trajectory, as described by the Gestalt law of good continuation. Abrupt changes of curvature strongly diminish contour salience. Here we show that by inserting local corner elements at points of angular discontinuity, a jagged contour becomes as salient as a straight one. We report results from detection experiments for contours with and without corner elements which indicate their psychophysical equivalence. This presents a challenge to the notion that contour integration mostly relies on local interactions between neurons tuned to single orientations, and suggests that a site where single orientations and more complex local features are combined constitutes the early basis of contour and 2D shape processing.

The Composite Effect Is Face-Specific in Young but Not Older Adults

In studying holistic face processing across the life-span there are only few attempts to separate face-specific from general aging effects. Here we used the complete design of the composite paradigm (Cheung et al., 2008) with faces and novel non-face control objects (watches) to investigate composite effects in young (18–32 years) and older adults (63–78 years). We included cueing conditions to alert using a narrow or a wide attentional focus when comparing the composite objects, and used brief and relaxed exposure durations for stimulus presentation. Young adults showed large composite effects for faces, but none for watches. In contrast, older adults showed strong composite effects for faces and watches, albeit the effects were larger for faces. Moreover, composite effects for faces were larger for the wide attentional focus in both age groups, while the composite effects for watches of older adults were alike for both cueing conditions. Older adults showed low accuracy at the same levels for both types of stimuli when attended and non-attended halves were incongruent. Increasing presentation times improved performance strongly for congruent but not for incongruent composite objects. These findings suggest that the composite effects of older adults reflect substantial decline in the ability to control irrelevant stimuli, which takes effect both in non-face objects and in faces. In young adults, highly efficient attentional control mostly precludes interference of irrelevant features in novel objects, thus their composite effects reflect holistic integration specific for faces or objects of expertise.

Gendered pathways to young adult symptomatology

The transition to adulthood is a critical juncture in the course of psychopathology. This study examined the ways in which earlier capacity to deal with relationship stress during adolescence contributed to an adaptive outcome in emerging adulthood. In a prospective study of 145 individuals, relationship stress, individual coping capacities, and perceived support from fathers, mothers, and peers were analyzed, when the participants were 13 and 17 years old. The effects of these earlier capacities to deal with relationship stress on health outcomes were examined in young adulthood (age 23). Gendered pathways to young adults’ symptomatology emerged. Females experiencing earlier relationship stress, but also support by mothers, fathers, and friends, showed less symptomatology at age 23. In addition, females’ withdrawal coping mediated the impact of stressful encounters on later internalizing symptomatology. In contrast, earlier coping with relationship stress was not found to be predictive for males. Earlier support from parents or friends was associated with later externalizing symptomatology in young men. Reasons for the gender-specific pathways to symptomatology are discussed.

Therapeutenbegleitete und patientengeleitete Exposition bei Panikstörung mit Agoraphobie

Zusammenfassung. Theoretischer Hintergrund: Die Exposition gilt als hoch wirksames Therapieelement in der Behandlung der Panikstörung mit Agoraphobie. Es ist jedoch weitgehend unklar, wie häufig und mit welchen Effekten verschiedene Modalitäten der Exposition (therapeutenbegleitet vs. patientengeleitet) in der Routineversorgung durchgeführt werden. Fragestellung: Es sollen Häufigkeit und Wirksamkeit der verschiedenen Durchführungsmodalitäten von Exposition in der Routinebehandlung der Panikstörung mit Agoraphobie untersucht werden. Methode: Bei N = 93 konsekutiven Patienten einer Hochschulambulanz mit der Hauptdiagnose Panikstörung mit Agoraphobie wurden Prä-Post-Veränderungen der Angstsymptomatik in Abhängigkeit von verschiedenen Expositionsmodalitäten erfasst. Die Auswirkungen von therapeutenbegleiteter und patientengeleiteter Exposition wurden getrennt für In-vivo-Exposition und interozeptive Exposition (IE) untersucht. Ergebnisse: Mit einer Kombination aus therapeutenbegleiteter und patientengeleiteter Exposition ließen sich tendenziell die besseren Therapieergebnisse erzielen, dieser Effekt ließ sich sowohl für die In-vivo-Exposition als auch für die IE nachweisen. Schlussfolgerung: Nach Möglichkeit sollten In-vivo-Exposition sowie IE sowohl therapeutenbegleitet als auch zusätzlich patientengeleitet (als selbständige Hausaufgabe) durchgeführt werden.

Recanalization Therapies in Acute Ischemic Stroke Patients

Background—

We explored the safety of intravenous thrombolysis (IVT) or intra-arterial treatment (IAT) in patients with ischemic stroke on non-vitamin K antagonist oral anticoagulants (NOACs, last intake <48 hours) in comparison with patients (1) taking vitamin K antagonists (VKAs) or (2) without previous anticoagulation (no-OAC).

Methods and Results—

This is a multicenter cohort pilot study. Primary outcome measures were (1) occurrence of intracranial hemorrhage (ICH) in 3 categories: any ICH (ICH any ), symptomatic ICH according to the criteria of the European Cooperative Acute Stroke Study II (ECASS-II) (sICH ECASS-II ) and the National Institute of Neurological Disorders and Stroke (NINDS) thrombolysis trial (sICH NINDS ); and (2) death (at 3 months). Cohorts were compared by using propensity score matching. Our NOAC cohort comprised 78 patients treated with IVT/IAT and the comparison groups of 441 VKA patients and 8938 no-OAC patients. The median time from last NOAC intake to IVT/IAT was 13 hours (interquartile range, 8–22 hours). In VKA patients, median pre-IVT/IAT international normalized ratio was 1.3 (interquartile range, 1.1–1.6). ICH any was observed in 18.4% NOAC patients versus 26.8% in VKA patients and 17.4% in no-OAC patients. sICH ECASS-II and sICH NINDS occurred in 2.6%/3.9% NOAC patients, in comparison with 6.5%/9.3% of VKA patients and 5.0%/7.2% of no-OAC patients, respectively. At 3 months, 23.0% of NOAC patients in comparison with 26.9% of VKA patients and 13.9% of no-OAC patients had died. Propensity score matching revealed no statistically significant differences.

Conclusions—

IVT/IAT in selected patients with ischemic stroke under NOAC treatment has a safety profile similar to both IVT/IAT in patients on subtherapeutic VKA treatment or in those without previous anticoagulation. However, further prospective studies are needed, including the impact of specific coagulation tests.

The sensitivity to replacement and displacement of the eyes region in early adolescence, young and later adulthood

Recent evidence suggests a rather gradual developmental trajectory for processing vertical relational face information, lasting well into late adolescence (de Heering and Schlitz, 2008). Results from another recent study (Tanaka et al., 2014) indicate that children and young adolescents use a smaller spatial integration field for faces than do adults, which particularly affects assessment of long-range vertical relations. Here we studied sensitivity to replacement of eyes and eyebrows (F), variation of inter-eye distance (H), and eye height (V) in young adolescents (11-12 years), young (21-25 years), and middle-age adults (51-62 years). In order to provide a baseline for potential age effects the sensitivity to all three types of face manipulations was calibrated to equal levels for the young adults group. Both the young adolescents and the middle-age adults showed substantially lower sensitivity compared to young adults, but only the young adolescents had selective impairment for V relational changes. Their inversion effects were at similar levels for all types of face manipulations, while in both adult groups the inversion effects for V were considerably stronger than for H or F changes. These results suggest that young adolescents use a limited spatial integration field for faces, and have not reached a mature state in processing vertical configural cues. The H-V asymmetry of inversion effects found for both adult groups indicates that adults integrate across the whole face when they view upright stimuli. However, the notably lower sensitivity of middle-age adults for all types of face manipulations, which was accompanied by a strong general "same" bias, suggests early age-related decline in attending cues for facial difference.

Effects of Spatial Frequency Similarity and Dissimilarity on Contour Integration

We examined the effects of spatial frequency similarity and dissimilarity on human contour integration under various conditions of uncertainty. Participants performed a temporal 2AFC contour detection task. Spatial frequency jitter up to 3.0 octaves was applied either to background elements, or to contour and background elements, or to none of both. Results converge on four major findings. (1) Contours defined by spatial frequency similarity alone are only scarcely visible, suggesting the absence of specialized cortical routines for shape detection based on spatial frequency similarity. (2) When orientation collinearity and spatial frequency similarity are combined along a contour, performance amplifies far beyond probability summation when compared to the fully heterogenous condition but only to a margin compatible with probability summation when compared to the fully homogenous case. (3) Psychometric functions are steeper but not shifted for homogenous contours in heterogenous backgrounds indicating an advantageous signal-to-noise ratio. The additional similarity cue therefore not so much improves contour detection performance but primarily reduces observer uncertainty about whether a potential candidate is a contour or just a false positive. (4) Contour integration is a broadband mechanism which is only moderately impaired by spatial frequency dissimilarity.

The complete design in the composite face paradigm: role of response bias, target certainty, and feedback

Some years ago an improved design (the “complete design”) was proposed to assess the composite face effect in terms of a congruency effect, defined as the performance difference for congruent and incongruent target to no-target relationships (Cheung et al., 2008). In a recent paper Rossion (2013) questioned whether the congruency effect was a valid hallmark of perceptual integration, because it may contain confounds with face-unspecific interference effects. Here we argue that the complete design is well-balanced and allows one to separate face-specific from face-unspecific effects. We used the complete design for a same/different composite stimulus matching task with face and non-face objects (watches). Subjects performed the task with and without trial-by-trial feedback, and with low and high certainty about the target half. Results showed large congruency effects for faces, particularly when subjects were informed late in the trial about which face halves had to be matched. Analysis of response bias revealed that subjects preferred the “different” response in incongruent trials, which is expected when upper and lower face halves are integrated perceptually at the encoding stage. The results pattern was observed in the absence of feedback, while providing feedback generally attenuated the congruency effect, and led to an avoidance of response bias. For watches no or marginal congruency effects and a moderate global “same” bias were observed. We conclude that the congruency effect, when complemented by an evaluation of response bias, is a valid hallmark of feature integration that allows one to separate faces from non-face objects.

Holistic face perception in young and older adults: effects of feedback and attentional demand

Evidence exists for age-related decline in face cognition ability. However, the extents to which attentional demand and flexibility to adapt viewing strategies contribute to age-related decline in face cognition tests is poorly understood. Here, we studied holistic face perception in older (age range 65–78 years, mean age 69.9) and young adults (age range 20–32 years, mean age 23.1) using the complete design for a sequential study-test composite face task (Richler et al., 2008b). Attentional demand was varied using trials that required participants to attend to both face halves and to redirect attention to one face half during the test (high attentional demand), and trials that allowed participants to keep a pre-adjusted focus (low attentional demand). We also varied viewing time and provided trial-by-trial feedback or no feedback. We observed strong composite effects, which were larger for the elderly in all conditions, independent of viewing time. Composite effects were smaller for low attentional demand, and larger for high attentional demand. No age-related differences were found in this respect. Feedback also reduced the composite effects in both age groups. Young adults could benefit from feedback in conditions with low and high attentional demands. Older adults performed better with feedback only in trials with low attentional demand. When attentional demand was high, older adults could no longer use the feedback signal, and performed worse with feedback than without. These findings suggest that older adults tend to use a global focus for faces, albeit piecemeal analysis is required for the task, and have difficulties adapting their viewing strategies when task demands are high. These results are consistent with the idea that elderly rely more on holistic strategies as a means to reduce perceptual and cognitive load when processing resources are limited (Konar et al., 2013).

Holistic processing and reliance on global viewing strategies in older adults' face perception

There is increasing evidence that face recognition might be impaired in older adults, but it is unclear whether the impairment is truly perceptual, and face specific. In order to address this question we compared performance in same/different matching tasks with face and non-face objects (watches) among young (mean age 23.7) and older adults (mean age 70.4) using a context congruency paradigm (Meinhardt-Injac, Persike & Meinhardt, 2010, Meinhardt-Injac, Persike and Meinhardt, 2011a). Older adults were less accurate than young adults with both object classes, while face matching was notably impaired. Effects of context congruency and inversion, measured as the hallmarks of holistic processing, were equally strong in both age groups, and were found only for faces, but not for watches. The face specific decline in older adults revealed deficits in handling internal facial features, while young adults matched external and internal features equally well. Comparison with non-face stimuli showed that this decline was face specific, and did not concern processing of object features in general. Taken together, the results indicate no age-related decline in the capabilities to process faces holistically. Rather, strong holistic effects, combined with a loss of precision in handling internal features indicate that older adults rely on global viewing strategies for faces. At the same time, access to the exact properties of inner face details becomes restricted.

A Slippery Slope: Estimated Slant of Hills Increases with Distance

The slopes of hills tend to be greatly overestimated. Previous studies have found that slope estimates are significantly greater when estimated verbally than with a proprioceptive measure. It has yet to be determined whether these estimates are made for the entire extent of the slope, or whether the estimates in closest proximity are estimated using a different process. Since some parietal cortex neurons respond differently to objects within arm's reach, short-distance slope estimation may utilize these or analogous neurons. Alternatively, greater implied effort might make longer slopes seem steeper. We determined that both verbal and proprioceptive reports of slope are overestimates that increase logarithmically with distance from the observer, contradicting both theories. Consistent with previous work, proprioceptive estimates were more accurate at all ranges. Our results can be interpreted as a function of the angle between the observer's gaze and the plane of the hill, modified by depth cues available at only near distances.

Integration of internal and external facial features in 8- to 10-year-old children and adults

Investigation of whole-part and composite effects in 4- to 6-year-old children gave rise to claims that face perception is fully mature within the first decade of life (Crookes & McKone, 2009). However, only internal features were tested, and the role of external features was not addressed, although external features are highly relevant for holistic face perception (Sinha & Poggio, 1996; Axelrod & Yovel, 2010, 2011). In this study, 8- to 10-year-old children and adults performed a same-different matching task with faces and watches. In this task participants attended to either internal or external features. Holistic face perception was tested using a congruency paradigm, in which face and non-face stimuli either agreed or disagreed in both features (congruent contexts) or just in the attended ones (incongruent contexts). In both age groups, pronounced context congruency and inversion effects were found for faces, but not for watches. These findings indicate holistic feature integration for faces. While inversion effects were highly similar in both age groups, context congruency effects were stronger for children. Moreover, children's face matching performance was generally better when attending to external compared to internal features. Adults tended to perform better when attending to internal features. Our results indicate that both adults and 8- to 10-year-old children integrate external and internal facial features into holistic face representations. However, in children's face representations external features are much more relevant. These findings suggest that face perception is holistic but still not adult-like at the end of the first decade of life.

The face inversion effect in opponent-stimulus rivalry

The face inversion effect is regarded as a hallmark of face-specific processing, and can be observed in a large variety of visual tasks. Face inversion effects are also reported in binocular rivalry. However, it is unclear whether these effects are face-specific, and distinct from the general tendency of visual awareness to privilege upright objects. We studied continuous rivalry across more than 600 dominance epochs for each observer, having faces and houses rival against their inverted counterparts, and letting faces rival against houses in both upright and inverted orientation. We found strong inversion effects for faces and houses in both the frequency of dominance epochs and their duration. Inversion effects for faces, however, were substantially larger, reaching a 70:30 distribution of dominance times for upright versus inverted faces, while a 60:40 distribution was obtained for upright versus inverted houses. Inversion effects for faces reached a Cohen's d of 0.85, compared to a value of 0.33 for houses. Dominance times for rivalry of faces against houses had a 60:40 distribution in favor of faces, independent of the orientation of the objects. These results confirm the general tendency of visual awareness to prefer upright objects, and demonstrate the outstanding role of faces. Since effect size measures clearly distinguish face stimuli in opponent-stimulus rivalry, the method is highly recommended for testing the effects of face manipulations against non-face reference objects.

The preview benefit for familiar and unfamiliar faces

Previewing distracters improves visual search - the preview benefit (Watson & Humphreys, 1997). Recent fMRI evidence suggests that the preview benefit rests on active inhibition in brain regions concerned with spatial memory, as well as in content selective areas (Allen, Humphreys, & Matthews, 2008). Using familiar and unfamiliar faces in a preview search task we show that search performance is much better with familiar than with unfamiliar faces. With both types of stimuli we obtained preview benefits of at least 10%, measured in terms of the advantage in reaction time relative to the no preview condition. The preview benefit increased up to 30% when distracter faces and their locations were previewed, compared to a benefit in the range of 10-25% for previewing just distracter locations. Analysis in terms of search time per item showed that familiar faces were processed with more than double the efficiency of the unfamiliar faces. Further, efficiency was enhanced relative to the no preview condition only when distracter locations and content were previewed, but not when participants previewed just distracter locations. These findings corroborate that the preview benefit involves both spatial and content-specific mechanisms, and indicate contribution of existing long-term memory representations independent of spatial memory.

Holistic Face Processing is Induced by Shape and Texture

There is increasing evidence that shape and texture are integral parts of face identity. However, it is less clear whether face-specific processing mechanisms are triggered by face shape alone, or if texture might play an important role. We address this question by studying mechanisms involved in holistic face processing. Face stimuli were either full-color pictures of real faces (shape and texture) or line drawings of the same faces (shape without texture). In a change detection task subjects judged whether eyes and eyebrows in two otherwise identical, sequentially presented faces were different in size or not. Afterwards, subjects had to identify the just presented face among two distractor faces (forced-choice identification task). The results obtained from the two tasks give rise to the conclusion that face identification and change detection tasks engage different processing strategies, which capture different aspects of holistic processing. Real faces were processed holistically, irrespective of task requirements, whereas line drawings were processed holistically only if face identification was required. On the basis of the data we conclude that face shape is relevant for the initial processing stage and feature binding, whereas face texture seems to be involved in processing of face configuration more specifically. Moreover, results demonstrate considerable flexibility of the face processing systems allowing for goal-directed and task-specific recall of face information.

Differences in agency? How adolescents from 18 countries perceive and cope with their futures

This study investigated how N = 5,126 adolescents (mean age of 15 years) from 18 countries perceive and cope with future- and school-related stress. The adolescents completed the Problem Questionnaire (PQ), which assesses stress, and the Coping Across Situations Questionnaire (CASQ), which assesses three coping styles (reflection/support-seeking, emotional outlet, and withdrawal/denial). Across countries, adolescents reported considerably higher levels of future-related stress than school-related stress. The adolescents actively coped with stressors in both domains and seldom relied on emotional outlet or withdrawal/denial. A clustering of the countries according to socioeconomic criteria and geographical proximity demonstrated that adolescents from the continental group of countries showed low stress and high coping. Adolescents in the east/Asia group showed medium stress and low coping and those in the south group showed high stress and low coping. Developmental context was more strongly associated with stress perception and coping, style than age or gender, a finding relevant for prevention approaches aiming to endorse positive orientation to the future and improve coping competence.

The time course of face matching for featural and relational image manipulations

It was found recently that horizontal and vertical relationships of facial features are differently vulnerable to inversion (Goffaux & Rossion, 2007). When faces are upside down manipulations of vertical relations are difficult to detect, while only moderate performance deficits are found for manipulations of horizontal relations, or when features differ. We replicate the findings of Goffaux and Rossion, and record the temporal courses of face matching performance and the effects of inversion. For vertical relations and featural changes inversion effects arise immediately, starting with the first 50ms of processing. For horizontal relations inversion effects are absent at brief timings, but arise later, after about 200ms. The final magnitudes of inversion effects are different in all three conditions, reaching 23.4% for vertical displacement, 10.7% for feature replacement, and 5.8% for horizontal displacement. Our results underline the special status of horizontal in contrast to vertical feature relations, and indicate that local and global configural information is handled in parallel by specific routines, as proposed recently (Senunkova & Barton, 2008).

The time course of face matching by internal and external features: Effects of context and inversion

Effects of context and inversion were studied in face matching tasks by measuring proportion correct as a function of exposure duration. Subjects were instructed to attend either internal features (task A) or external features (task B) and matched two consecutive face stimuli, which included either congruent, incongruent, or no facial context features. In congruent contexts matching performance rose fast and took very similar courses for both types of facial features. With no contexts internal and external features were found to be matched at an equal speed, while incongruent contexts seriously delayed matching performance for internal, but not for external features. Analysing the effects of context and inversion showed strong interactions with time scale and the features to be attended. At brief timings effects of inversion and context were strong for both feature types. At longer exposure durations there were pronounced effects of inversion and context for internal features while for external features inversion effects were absent and context effects at just moderate degrees. Moreover, deteriorating effects of incongruent contexts, which were strong at brief timings, were attenuated at longer exposure durations, while facilitative effects of congruent contexts resided at high levels. These findings indicate that global and holistic processing modes dominate the early epoch of the face specific visual response, but can be replaced by modes that allow observers to regulate contextual influences and to access facial features more focused when the first 200 ms have passed.

One-on-one long-term tutorials in general practitioners' practices - a successful new teaching concept in primary care medicine

To improve teaching in practical and communicative skills and knowledge in day-to-day medical practice, in 1997 we introduced one-on-one tutorials in general practitioners' offices as a mandatory part of medical students' academic education. Students participate actively half a day per week in their 3rd and 4th academic years (out of 6) in the office or clinic of a trained personal tutor. We recruited 270 general practitioners in town or from surrounding rural areas for this purpose. 85% of students choose general practitioners as their tutors and 15 % tutors in hospitals. To test whether the tutorials' aims were achieved, in 2005 we performed a detailed questionnaire evaluation after seven years' experience of one-on-one tutorials. All 236 students involved were asked to participate. The response rate was almost complete (98%). 233 anonymous questionnaires were analysed. Students reported improvement in knowledge, social and communicative skills and personal motivation. The overall rating of the one-on-one tutorials obtained 5.3 on a 6 point scale and achieved the top ranking among all university medical faculty classes. In-practice long-term one-on-one medical student-general practitioner tutorials can be recommended for implementation.

Cue summation enables perceptual grouping

In order to study how basic features interact in shape perception, subjects detected target figure presence and identified target figure shape in a combined 2-alternative forced-choice task. Target figures were embedded in Gabor random fields and were defined by feature contrast in spatial frequency, orientation, or both. Two figure classes were used: block figures, which could not be identified at low feature-contrast levels, and lozenge figures, which could be identified to a moderate degree. Results showed a substantial double-cue benefit for both figure classes in detection. In identification, however, a double-cue benefit was practically absent for blocks, whereas, for lozenges, cue summation proved to be much stronger than in detection. The finding that the way basic features interact is modulated by figure class and psychophysical task indicates involvement of 2 distinct perceptual mechanisms in shape perception. The 1st one highlights salient features and enables local grouping on an early feature-specific processing level. The 2nd one is higher level, serves form completion and grouping of salient contours into global shapes, and enables figure perception.

Cue combination in a combined feature contrast detection and figure identification task

Target figures defined by feature contrast in spatial frequency, orientation or both cues had to be detected in Gabor random fields and their shape had to be identified in a dual task paradigm. Performance improved with increasing feature contrast and was strongly correlated among both tasks. Subjects performed significantly better with combined cues than with single cues. The improvement due to cue summation was stronger than predicted by the assumption of independent feature specific mechanisms, and increased with the performance level achieved with single cues until it was limited by ceiling effects. Further, cue summation was also strongly correlated among tasks: when there was benefit due to the additional cue in feature contrast detection, there was also benefit in figure identification. For the same performance level achieved with single cues, cue summation was generally larger in figure identification than in feature contrast detection, indicating more benefit when processes of shape and surface formation are involved. Our results suggest that cue combination improves spatial form completion and figure-ground segregation in noisy environments, and therefore leads to more stable object vision.

Synergy of features enables detection of texture defined figures

Traditional theories of early visual processing suggest that elementary visual features are handled in parallel by independent neural pathways. We studied the interaction of orientation and spatial frequency in the discrimination of Gabor random fields. Target textures differed from reference textures either in mean feature value, showing an edge-like transition between both textures (edge defined), or in the degree of feature homogeneity with smooth transitions (region defined). Irrespective of the kind of texture definition, we found strong cue summation for targets defined by both cues simultaneously, provided two conditions were fulfilled. First, they were barely discriminable when defined by one cue alone. Second, the target elements formed a closed 2D surface. Only marginal cue summation was observed when target elements were heterogeneously distributed in a predefined area, lacking a clear 2D shape. Our findings indicate that feature synergy enables figure-ground segregation when the information from independent feature-specific pathways is insufficient for solving this task.

Feature synergy depends on feature contrast and objecthood

Pairs of texture figures, defined by contrast in spatial frequency, orientation or both cues (redundant texture definition) had to be detected within a homogeneous Gabor field. In line with expectation we find better detection performance for arrangements with higher feature contrast along the border where the figures abut. Redundantly defined figures show synergy, a significant performance increase compared to the prediction of independent processing of orientation and spatial frequency cues. As found in previous studies [Spatial Vision 16 (2003) 459; Vision Research (submitted for publication)] this performance advantage is negatively correlated with visibility. In particular, figures with high border feature contrast are easily detectable but show weak synergy whereas figures with low border feature contrast are barely detectable but remarkably benefit from redundant texture definition. Closer analysis reveals that the form of the figures is also crucial: As long as they maintain a clear two dimensional shape the synergy effect is only marginally affected by variation figure size and border length. But when they degrade to one dimensional Gabor element arrays, synergy almost completely vanishes. The results imply that both factors, low visibility and objecthood, are critical for feature synergy. We conclude that facilitation across feature domains serves to segregate figure from ground when the signal from a single domain is too weak to enable object detection and vanishes under conditions of stable object vision.

Strength of feature contrast mediates interaction among feature domains

Traditional theories of texture segregation suggest that elementary visual features are processed in parallel by independent modules at early visual stages. Here we show that, for small feature contrasts and large values evoking perceptual popout, different forms of module interaction exist. While discrimination of highly salient features rests on independent feature specific pathways, information is summed across domains when barely noticeable ones are to be detected in homogeneous textures.